STRESS CRACKING OF POLYAMIDES BY METAL SALTS .I. METAL HALIDES

The stress cracking of polyamides (nylons) by a number of metal salts, in aqueous and nonaqueous solutions, has been investigated. Many metal halides and halide‐like salts were found to be active stress‐cracking agents, while metal acetates and sulfates were inactive. Zinc chloride was found to be most active, and its activity was compared with other metal halides. Using a recording tensometer, time to crack initiation, time to crack‐through and time to rupture were determined. These parameters were found to be dependent on temperature, moisture content of the nylon, concentration of the cracking agent and level of stress. High values of all these factors favored rapid cracking. Cracking parameters were shown to be mainly independent of the surface geometry of the nylon and the hydrogen ion concentration of the cracking agent. Metal halides did not appear to cause any chain scission in the nylon and stress cracking was not due to hydrolysis or metal‐ion catalysed hydrolysis. Copyright © 1969 John Wiley & Sons, Inc.